Saturday, February 28, 2009

Reporting from Washington -- Not since Lyndon B. Johnson and Franklin D. Roosevelt has a president moved to expand the role of government so much on so many fronts -- and with such a demanding sense of urgency.

The scope of President Obama's ambition was laid bare in the budget blueprint issued Thursday.

The budget would account for 24.1% of next year's estimated gross domestic product, one of the highest percentages since World War II, and would raise taxes, redistribute income, spend more on social programs than on defense, and implement policies that touch almost every aspect of Americans' lives -- their banks, healthcare, schools, even the air they breathe.

Even more stark than the breadth and scale of Obama's proposals was his determination to break with the conservative principles that have dominated national politics and policymaking since Ronald Reagan's election as president in 1980.

"It changes the whole paradigm," said Sen. Charles E. Schumer (D-N.Y.). "We're going to have a government that helps people."

House Minority Leader John A. Boehner (R-Ohio) took another view. "The era of big government is back, and Democrats are asking you to pay for it," he said.

Obama's budget plan asserts that in some areas, government can do a better job than private enterprise and do it for less. For instance, he argues, Washington can provide loans to college students just as efficiently and at lower cost than the private lenders who dominate the field.

And after years of steady growth in the share of the nation's wealth owned by its most affluent citizens, Obama is calling for tax changes that would require high-income taxpayers to shoulder more of the load.

The question now is whether Congress will go along.

The question applies, in particular, to Blue Dog Democrats, members of the House and Senate who in recent years have won election from traditionally conservative and Republican areas by positioning themselves as moderate to conservative, especially on spending and the deficit.

Although Obama's supporters enjoy a comfortable margin in the House, his $787-billion economic stimulus package passed the Senate only after a deal was struck with conservative Democrats and three moderate Republicans.

As a candidate, Obama often staked out positions so general or nuanced that voters often inferred that he agreed with them even though he had not quite said so. That approach broadened his appeal. And in his first five weeks as president, Obama largely continued that approach, signaling that he was willing to listen to all sides and using his choice of Cabinet members to strike balances among different interest groups.

That stage of his presidency appears to be ending. The budget outline suggests that Obama is ready to start spending his political capital -- a recent Gallup poll found that 67% of Americans approved of the way he was handling the stimulus bill -- and risk making enemies in the pursuit of ambitious policy goals.

The breadth of the budget has an advantage: Even if Obama achieves only part of his goals, that could leave a long record of accomplishment. But by proposing action on such a wide range of fronts, Obama also risks overloading the often cumbersome legislative machinery of Capitol Hill.

"I cannot remember a time when Congress had an agenda of this scope, size and difficulty," said former Rep. Lee H. Hamilton, an Indiana Democrat who spent 34 years in the House.

He compared the magnitude of Obama's agenda to that of Johnson's Great Society, which launched a costly war on poverty and pushed through the most far-reaching civil rights laws since President Lincoln.

Obama has already demonstrated an ability to get Congress to break its institutional inertia. The economic stimulus was one of the biggest bills in history, and it made it through the congressional maze in record time.

Part of his approach to achieving that was to set the broad parameters of the initiative and leave it to congressional Democrats to fill in the details. On the stimulus, no detail seemed more important to Obama than two demands: The package had to be big, and it had to be approved quickly.

In the new budget blueprint -- a basic outline of the budget to be submitted to Congress in April -- Obama has similarly left it to Congress to write the details of his healthcare initiative. But he wants it at the top of Capitol Hill's agenda.

"The urgency on healthcare is now," said Sen. Ron Wyden (D-Ore.). "After 60 years of yakking about healthcare, he's saying, 'I don't want to wait for year 61.' "

All this has left Republicans largely on the sidelines, despite earlier talk about a new era of bipartisanship. Indeed, the budget's sharp U-turn away from conservative principles shows how willing Obama is to confront Republicans directly.

Obama's leadership style is a far cry from other recent presidents, like Bill Clinton, who declared "The era of big government is over" and made an art form of proposing modest initiatives, such as requiring school uniforms as a step toward improving education.

Some in Washington were surprised by the budget because Obama's approach often blurs distinctions rather than highlights them.

But in writing this budget, he had to drop the shades of gray because a budget is all numbers in black and white. Either spending for defense goes up or down; taxes are raised or they are cut.

Although Obama has tried to cut a nonideological profile and has staffed his administration with many moderates, much of his budget reflects liberal ideals.

He says government can do some things better and cheaper than the private sector. He embraces income redistribution of sorts by proposing to pay for his healthcare initiative with increasing taxes on the wealthy.

And without apology, the budget document essentially declared the end of an era: "The past eight years have discredited once and for all the philosophy of trickle-down economics -- that tax breaks, income gains and wealth creation among the wealthy eventually will work their way down to the middle class."

The budget would account for 24.1% of next year's estimated gross domestic product, one of the highest percentages since World War II, and would raise taxes, redistribute income, spend more on social programs than on defense, and implement policies that touch almost every aspect of Americans' lives -- their banks, healthcare, schools, even the air they breathe.

Even more stark than the breadth and scale of Obama's proposals was his determination to break with the conservative principles that have dominated national politics and policymaking since Ronald Reagan's election as president in 1980.

"It changes the whole paradigm," said Sen. Charles E. Schumer (D-N.Y.). "We're going to have a government that helps people."

House Minority Leader John A. Boehner (R-Ohio) took another view. "The era of big government is back, and Democrats are asking you to pay for it," he said.

Obama's budget plan asserts that in some areas, government can do a better job than private enterprise and do it for less. For instance, he argues, Washington can provide loans to college students just as efficiently and at lower cost than the private lenders who dominate the field.

And after years of steady growth in the share of the nation's wealth owned by its most affluent citizens, Obama is calling for tax changes that would require high-income taxpayers to shoulder more of the load.

The question now is whether Congress will go along.

The question applies, in particular, to Blue Dog Democrats, members of the House and Senate who in recent years have won election from traditionally conservative and Republican areas by positioning themselves as moderate to conservative, especially on spending and the deficit.

Although Obama's supporters enjoy a comfortable margin in the House, his $787-billion economic stimulus package passed the Senate only after a deal was struck with conservative Democrats and three moderate Republicans.

As a candidate, Obama often staked out positions so general or nuanced that voters often inferred that he agreed with them even though he had not quite said so. That approach broadened his appeal. And in his first five weeks as president, Obama largely continued that approach, signaling that he was willing to listen to all sides and using his choice of Cabinet members to strike balances among different interest groups.

That stage of his presidency appears to be ending. The budget outline suggests that Obama is ready to start spending his political capital -- a recent Gallup poll found that 67% of Americans approved of the way he was handling the stimulus bill -- and risk making enemies in the pursuit of ambitious policy goals.

The breadth of the budget has an advantage: Even if Obama achieves only part of his goals, that could leave a long record of accomplishment. But by proposing action on such a wide range of fronts, Obama also risks overloading the often cumbersome legislative machinery of Capitol Hill.

"I cannot remember a time when Congress had an agenda of this scope, size and difficulty," said former Rep. Lee H. Hamilton, an Indiana Democrat who spent 34 years in the House.

He compared the magnitude of Obama's agenda to that of Johnson's Great Society, which launched a costly war on poverty and pushed through the most far-reaching civil rights laws since President Lincoln.

Obama has already demonstrated an ability to get Congress to break its institutional inertia. The economic stimulus was one of the biggest bills in history, and it made it through the congressional maze in record time.

Part of his approach to achieving that was to set the broad parameters of the initiative and leave it to congressional Democrats to fill in the details. On the stimulus, no detail seemed more important to Obama than two demands: The package had to be big, and it had to be approved quickly.

In the new budget blueprint -- a basic outline of the budget to be submitted to Congress in April -- Obama has similarly left it to Congress to write the details of his healthcare initiative. But he wants it at the top of Capitol Hill's agenda.

"The urgency on healthcare is now," said Sen. Ron Wyden (D-Ore.). "After 60 years of yakking about healthcare, he's saying, 'I don't want to wait for year 61.' "

All this has left Republicans largely on the sidelines, despite earlier talk about a new era of bipartisanship. Indeed, the budget's sharp U-turn away from conservative principles shows how willing Obama is to confront Republicans directly.

Obama's leadership style is a far cry from other recent presidents, like Bill Clinton, who declared "The era of big government is over" and made an art form of proposing modest initiatives, such as requiring school uniforms as a step toward improving education.

Some in Washington were surprised by the budget because Obama's approach often blurs distinctions rather than highlights them.

But in writing this budget, he had to drop the shades of gray because a budget is all numbers in black and white. Either spending for defense goes up or down; taxes are raised or they are cut.

Although Obama has tried to cut a nonideological profile and has staffed his administration with many moderates, much of his budget reflects liberal ideals.

He says government can do some things better and cheaper than the private sector. He embraces income redistribution of sorts by proposing to pay for his healthcare initiative with increasing taxes on the wealthy.

And without apology, the budget document essentially declared the end of an era: "The past eight years have discredited once and for all the philosophy of trickle-down economics -- that tax breaks, income gains and wealth creation among the wealthy eventually will work their way down to the middle class."

USAir Flight 1549 Detours Through New Jersey Town

We don't know who took these photos, but the strange journey of USAirways Flight 1549 continues... this time through the downtown wilds of suburban New Jersey.

You remember Flight 1549, of course -- that was the Airbus A320, that took off from New York's LaGuardia Airport and then landed unexpectedly (if fortuitously) in the Hudson River. After the aircraft was recovered from the drink, it was hauled to the Garden State on a barge. And after it was removed from the barge, it was partially disassembled and transported by truck through the narrow streets of East Rutherford, NJ -- a town best known as the home of the Meadowlands sports arena complex.

The infamous US Airways jet that plunged from the sky into the Hudson River last month took another trip recently — this time down Park Avenue in East Rutherford.

“I was in complete shock when I saw the jet coming down the street,” said North Arlington resident Jessica Cates.

Since the accident last month, the airplane had been stationed at a barge in Jersey City, after being plucked from the icy Hudson River. Moving to a more permanent home, the jet was transported via a police motorcade and flat-bed truck to its long-term resting place in Harrison.

“It was moved to a salvage facility for storage and further evaluation,” said Ted Lopatkiewicz, spokesman for the National Transportation Safety Board, which is in charge of the investigation. “Up until now, it was sitting on a barge.”

A direct route from Jersey City to Harrison hit a snag Jan. 31 when an overpass along the way detoured the plane into East Rutherford, according to East Rutherford Deputy Police Chief Anthony Krupocin.

From Park Avenue, the plane traveled to Orient Way and then to Route 17 South. “Our officers assisted because the truck was moving slowly, but there were no delays on the roadway,” East Rutherford Police Chief Larry Minda said.

Recalling the unusual experience, Cates said she was dining at the Blarney Station on Park Avenue, when she exited the establishment and saw a number of motorcycles and police cars flashing their emergency lights.

At first, Cates said she thought there was an accident, but to her surprise, she ended up seeing the jet — missing the wings and tail — slowly passing by her eyes on a flat-bed truck.

“It was just so big,” Cates said. “It begs the question how they got (the plane) on the street.”

The plane will remain at the facility until the NTSB’s investigation is complete, which Lopatkiewicz estimated would take between nine and 12 months.

USAir Flight 1549 Detours Through New Jersey Town

We don't know who took these photos, but the strange journey of USAirways Flight 1549 continues... this time through the downtown wilds of suburban New Jersey.

You remember Flight 1549, of course -- that was the Airbus A320, that took off from New York's LaGuardia Airport and then landed unexpectedly (if fortuitously) in the Hudson River. After the aircraft was recovered from the drink, it was hauled to the Garden State on a barge. And after it was removed from the barge, it was partially disassembled and transported by truck through the narrow streets of East Rutherford, NJ -- a town best known as the home of the Meadowlands sports arena complex.

The infamous US Airways jet that plunged from the sky into the Hudson River last month took another trip recently — this time down Park Avenue in East Rutherford.

“I was in complete shock when I saw the jet coming down the street,” said North Arlington resident Jessica Cates.

Since the accident last month, the airplane had been stationed at a barge in Jersey City, after being plucked from the icy Hudson River. Moving to a more permanent home, the jet was transported via a police motorcade and flat-bed truck to its long-term resting place in Harrison.

“It was moved to a salvage facility for storage and further evaluation,” said Ted Lopatkiewicz, spokesman for the National Transportation Safety Board, which is in charge of the investigation. “Up until now, it was sitting on a barge.”

A direct route from Jersey City to Harrison hit a snag Jan. 31 when an overpass along the way detoured the plane into East Rutherford, according to East Rutherford Deputy Police Chief Anthony Krupocin.

From Park Avenue, the plane traveled to Orient Way and then to Route 17 South. “Our officers assisted because the truck was moving slowly, but there were no delays on the roadway,” East Rutherford Police Chief Larry Minda said.

Recalling the unusual experience, Cates said she was dining at the Blarney Station on Park Avenue, when she exited the establishment and saw a number of motorcycles and police cars flashing their emergency lights.

At first, Cates said she thought there was an accident, but to her surprise, she ended up seeing the jet — missing the wings and tail — slowly passing by her eyes on a flat-bed truck.

“It was just so big,” Cates said. “It begs the question how they got (the plane) on the street.”

The plane will remain at the facility until the NTSB’s investigation is complete, which Lopatkiewicz estimated would take between nine and 12 months.

The maze production house Team Of Monkeys has changed its name to Ink Blot Mazes. "This name change will streamline our brand recognition while at the same time helping us by defining our product within the name" said Yonatan Frimer, one of the artists at Ink Blot Mazes.

After being published since 2006 in various newspapers and magazines, Ink Blot Mazes has now begun licensing their mazes to activity work-booklets as well as increasing the number of publications and syndicates involved in publishing the mazes.

"The choice to pursue newspapers more aggressively comes at a good time." said Keith Nanwood, Marketing assistant at Ink Blot Mazes, "Print publication are suffering from their subscribers going more and more to the internet for their news. With the recent popularity of Sudoku, word finds, and now mazes, readers have a good reason to get a paper delivered everyday."

According to Marla Singer, Marketing Director at Inkblot Mazes, "Mazes, Sudoku, word finds and other puzzles are really the only interactive aspects of print media. With articles and comics, the reader just passively accepts the information. But with Sudoku or mazes, they take out their pen and 'interact with the paper.'"

Ink Blot Maze differ from normal mazes in that images are conformed from the shapes of the lines creating the path of the mazes. Their popularity is mainly due to their depiction of various celebrities as well as teams of monkeys achieving unusual tasks by working in a team.

Yonatan Frimer began drawing mazes in the 3rd grade out of boredom. Anytime his mind would wonder off he'd simply whisk away the boredom with a few mazing pencil strokes - they didn't let him write with pens, yet, at that age.

Fast forward about 20 years later to when Yonatan broke his leg in a motorcycle accident and was hospitalized and bed bound for nearly 3 years. Too keep his mind as busy as possible during the recovery period, he focused on drawing mazes. As much as 15 hours a day, pretty much everyday, for nearly 3 years. He also practiced drawing not just mazes, but also portraits and caricatures as well as anime and plain old comics, which he often incorporates into better maze making.

After making several hundred mazes and posting them to the internet, Yonatan began getting many request for printing his mazes from various newspapers and magazine publications, which has grown over time to include millions of copies in 5 countries!

Until 2009, most of the mazes where posted to Team Of Monkeys . com . In Feb 2009, the mazes where renamed under the brand Ink Blot Mazes along with a higher production rate to meet the demands of publications and syndicates.

Some Maze Videos:

How naming the maze can make the maze:

This is a maze I call "April Showers Bring MAZE Flowers".I usually try to work the word MAZE in a funny way into some normal saying or catch phrase

Mazerotti is intended to sound like Maserati, the exotic Italian sports car manufacturer.

Somewhere in storage, near a Mediterranean coast, I have a booklet of mazes I titles Maze AnatomyI guess you could call it a spin off the famous Anatomy Illustration Book, Grey's Anatomy.Drawing Anatomically correct biology illustrations is much harder than, and not nearly as much fun, as it looks.Here is one of the mazes from that collection: An Eukaryotic Cell. Can't imagine why these never really took off.I have recently begun publishing my mazes and am very interested in speaking with any publishers.

Dye-sensitized solar cell

A dye-sensitized solar cell (DSSc, DSC or DYSC[1]) is a relatively new class of low-cost solar cell, that belong to the group of thin-film solar cells.[2] It is based on a semiconductor formed between a photo-sensitized anode and an electrolyte, a photoelectrochemical system. This cell was invented by Michael Grätzel and Brian O'Regan at the École Polytechnique Fédérale de Lausanne in 1991[3] and are also known as Grätzel cells.

This cell is extremely promising because it is made of low-cost materials and does not need elaborate apparatus to manufacture. In bulk it should be significantly less expensive than older solid-state cell designs. It can be engineered into flexible sheets and is mechanically robust, requiring no protection from minor events like hail or tree strikes. Although its conversion efficiency is less than the best thin-film cells, its price/performance ratio (kWh/M2/annum) should be high enough to allow them to compete with fossil fuel electrical generation (grid parity). Commercial applications, which were held up due to chemical stability problems, are now forecast in the European Union Photovoltaic Roadmap to be a potentially significant contributor to renewable electricity generation by 2020.

Previous technology: semiconductor solar cells

In a traditional solid-state semiconductor, a solar cell is made from two doped crystals, one with a slight negative bias (n-type semiconductor), which has extra free electrons, and the other with a slight positive bias (p-type semiconductor), which is lacking free electrons. When placed in contact, some of the electrons in the n-type portion will flow into the p-type to "fill in" the missing electrons, also known as an electron hole. Eventually enough will flow across the boundary to equalize the Fermi levels of the two materials. The result is a region at the interface, the p-n junction, where charge carriers are depleted and/or accumulated on each side of the interface. In silicon, this transfer of electrons produces a potential barrier of about 0.6V to 0.7V[4].

When placed in the sun, photons in the sunlight can strike the bound electrons in the p-type side of the semiconductor, giving them more energy, a process known technically as photoexcitation. In silicon, sunlight can provide enough energy to push an electron out of the lower-energy valence band into the higher-energy conduction band. As the name implies, electrons in the conduction band are free to move about the silicon. When a load is placed across the cell as a whole, these electrons will flow out of the p-type side into the n-type side, lose energy while moving through the external circuit, and then back into the p-type material where they can once again re-combine with the valence-band hole they left behind. In this way, sunlight creates an electrical current.[4]

In any semiconductor, the bandgap means that only photons with that amount of energy, or more, will contribute to producing a current. In the case of silicon, the majority of visible light from red to violet has enough energy to make this happen. Unfortunately this also means that the higher energy photons, at the blue and violet end of the spectrum, have more than enough energy to cross the bandgap; although some of this extra energy is transferred into the electrons, the vast majority of it is wasted as heat. Another issue is that in order to have a reasonable chance of capturing a photon in the p-type layer it has to be fairly thick. This also increases the chance that a freshly-ejected electron will meet up with a previously-created hole in the material before reaching the p-n junction. These effects produce an upper limit on the efficiency of silicon solar cells, currently around 12% to 15% for common examples and up to 25% for the best laboratory modules.

By far the biggest problem with the conventional approach is cost; solar cells require a relatively thick layer of silicon in order to have reasonable photon capture rates, and silicon is an expensive commodity. There have been a number of different approaches to reduce this cost over the last decade, notably the thin-film approaches, but to date they have seen limited application due to a variety of practical problems. Another line of research has been to dramatically improve efficiency through the multi-junction approach, although these cells are very high cost and suitable only for large commercial deployments. In general terms the types of cells suitable for rooftop deployment have not changed significantly in efficiency, although costs have dropped somewhat due to increased supply.

[edit]DSC

Dye-sensitized solar cells separate the two functions provided by silicon in a traditional cell design. Normally the silicon acts as both the source of photoelectrons, as well as providing the electric field to separate the charges and create a current. In the dye-sensitized solar cell, the bulk of the semiconductor is used solely for charge transport, the photoelectrons are provided from a separate photosensitive dye. Charge separation occurs at the surfaces between the dye, semiconductor and electrolyte.

The dye molecules are quite small (nanometer sized), so in order to capture a reasonable amount of the incoming light the layer of dye molecules needs to be made fairly thick, much thicker than the molecules themselves. To address this problem, a nanomaterial is used as a scaffold to hold large numbers of the dye molecules in a 3-D matrix, increasing the number of molecules for any given surface area of cell. In existing designs, this scaffolding is provided by the semiconductor material, which serves double-duty.

Construction

In the case of the original Grätzel design, the cell has three primary parts. On the top is a transparent anode made of fluorine-doped tin oxide (SnO2:F) deposited on the back of a (typically glass) plate. On the back of the conductive plate is a thin layer of titanium dioxide (TiO2), which forms into a highly porous structure with an extremely high surface area. TiO2 only absorbs a small fraction of the solar photons (those in the UV).[5]

The plate is then immersed in a mixture of a photosensitive ruthenium-polypyridine dye (also called molecular sensitizers[5]) and a solvent. After soaking the film in the dye solution, a thin layer of the dye is left covalently bonded to the surface of the TiO2. A separate backing is made with a thin layer of the iodide electrolyte spread over a conductive sheet, typically platinum metal. The front and back parts are then joined and sealed together to prevent the electrolyte from leaking. The construction is simple enough that there are hobby kits available for hand-constructing them.[6] Although they use a number of "advanced" materials, these are inexpensive compared to the silicon needed for normal cells because they require no expensive manufacturing steps. TiO2, for instance, is already widely used as a paint base.

Operation

Sunlight enters the cell through the transparent SnO2:F top contact, striking the dye on the surface of the TiO2. Photons striking the dye with enough energy to be absorbed will create an excited state of the dye, from which an electron can be "injected" directly into the conduction band of the TiO2, and from there it moves by diffusion (as a result of an electron concentration gradient) to the clear anode on top.

Meanwhile, the dye molecule has lost an electron and the molecule will decompose if another electron is not provided. The dye strips one from iodide in electrolyte below the TiO2, oxidizing it into triiodide. This reaction occurs quite quickly compared to the time that it takes for the injected electron to recombine with the oxidized dye molecule, preventing this recombination reaction that would effectively short-circuit the solar cell.

The triiodide then recovers its missing electron by mechanically diffusing to the bottom of the cell, where the counter electrode re-introduces the electrons after flowing through the external circuit.

Efficiency

Main article: Solar conversion efficiency

There are several important measures that are used to characterize solar cells. The most obvious is the total amount of electrical power produced for a given amount of solar power shining on the cell. Expressed as a percentage, this is known as the solar conversion efficiency. Electrical power is the product of current and voltage, so the maximum values for these measurements are important as well, Jsc and Voc respectively. Finally, in order to understand the underlying physics, the "quantum efficiency" is used to compare the chance that one photon (of a particular energy) will create one electron.

In quantum efficiency terms, DSSc's are extremely efficient. Due to their "depth" in the nanostructure there is a very high chance that a photon will be absorbed, and the dyes are very effective at converting them to electrons. Most of the small losses that do exist in DSSc's are due to conduction losses in the TiO2 and the clear electrode, or optical losses in the front electrode. The overall quantum efficiency for green light is about 90%, with the "lost" 10% being largely accounted for by the optical losses in top electrode.[7] The quantum efficiency of traditional designs vary, depending on their thickness, but are about the same as the DSSc.

The maximum voltage generated by such a cell, in theory, is simply the difference between the (quasi-)Fermi level of the TiO2 and the redox potential of the electrolyte, about 0.7 V under solar illumination conditions (Voc). That is, if an illuminated DSSc is connected to a voltmeter in an "open circuit", it would read about 0.7 V. In terms of voltage, DSSc's offer slightly higher Voc than silicon, about 0.7 V compared to 0.6 V. This is a fairly small difference, so real-world differences are dominated by current production, Jsc.

Although the dye is highly efficient at turning absorbed photons into free electrons in the TiO2, it is only those photons which are absorbed by the dye that ultimately result in current being produced. The rate of photon absorption depends upon the absorption spectrum of the sensitized TiO2 layer and upon the solar flux spectrum. The overlap between these two spectra determines the maximum possible photocurrent. Typically used dye molecules generally have poorer absorption in the red part of the spectrum compared to silicon, which means that fewer of the photons in sunlight are usable for current generation. These factors limit the current generated by a DSSc, for comparison, a traditional silicon-based solar cell offers about 35 mA/cm², whereas current DSSc's offer about 20 mA/cm².

Combined with a fill factor of about 70%, overall peak power production for current DSSc's is about 11%.[8][9]

Degradation

DSSC degrades from UV light. The barrier may include UV stabilizers and/or UV absorbingluminescent chromophores (which emit at longer wavelengths) and antioxidants to protect and improve the efficiency of the cell [10].

Advantages and drawbacks

DSSc's are currently the most efficient third-generation solar technology available. Other thin-film technologies are typically around 8%, and traditional low-cost commercial silicon panels operate between 12% and 15%. This makes DSSc's attractive as a replacement for existing technologies in "low density" applications like rooftop solar collectors, where the mechanical robustness and light weight of the glass-less collector is a major advantage. They may not be as attractive for large-scale deployments where higher-cost higher-efficiency cells are more viable, but even small increases in the DSSc conversion efficiency might make them suitable for some of these roles as well.

There is another area where DSScs are particularly attractive. The process of injecting an electron directly into the TiO2 is qualitatively different to that occurring in a traditional cell, where the electron is "promoted" within the original crystal. In theory, given low rates of production, the high-energy electron in the silicon could re-combine with its own hole, giving off a photon (or other form of energy) and resulting in no current being generated. Although this particular case may not be common, it is fairly easy for an electron generated in another molecule to hit a hole left behind in a previous photoexcitation.

In comparison, the injection process used in the DSSc does not introduce a hole in the TiO2, only an extra electron. Although it is energetically possible for the electron to recombine back into the dye, the rate at which this occurs is quite slow compared to the rate that the dye regains an electron from the surrounding electrolyte. Recombination directly from the TiO2 to species in the electrolyte is also possible although, again, for optimized devices this reaction is rather slow.[11] On the contrary, electron transfer from the platinum coated electrode to species in the electrolyte is necessarily very fast.

As a result of these favorable "differential kinetics", DSSc's work even in low-light conditions. DSSc's are therefore able to work under cloudy skies and non-direct sunlight, whereas traditional designs would suffer a "cutout" at some lower limit of illumination, when charge carrier mobility is low and recombination becomes a major issue. The cutoff is so low they are even being proposed for indoor use, collecting energy for small devices from the lights in the house.[12]

A practical advantage, one DSSc's share with most thin-film technologies, is that the cell's mechanical robustness indirectly leads to higher efficiencies in higher temperatures. In any semiconductor, increasing temperature will promote some electrons into the conduction band "mechanically". The fragility of traditional silicon cells requires them to be protected from the elements, typically by encasing them in a glass box similar to a greenhouse, with a metal backing for strength. Such systems suffer noticeable decreases in efficiency as the cells heat up internally. DSSc's are normally built with only a thin layer of conductive plastic on the front layer, allowing them to radiate away heat much easier, and therefore operate at lower internal temperatures.

The major disadvantage to the DSSc design is the use of the liquid electrolyte, which has temperature stability problems. At low temperatures the electrolyte can freeze, ending power production and potentially leading to physical damage. Higher temperatures cause the liquid to expand, making sealing the panels a serious problem. Another major drawback is the electrolyte solution, which contains volatile organic solvents and must be carefully sealed. This, along with the fact that the solvents permeate plastics, has precluded large-scale outdoor application and integration into flexible structure.[13]

Replacing the liquid electrolyte with a solid has been a major ongoing field of research. Recent experiments using solidified melted salts have shown some promise, but currently suffer from higher degradation during continued operation, and are not flexible.[14]

Development

The dyes used in early experimental cells (circa 1995) were sensitive only in the high-frequency end of the solar spectrum, in the UV and blue. Newer versions were quickly introduced (circa 1999) that had much wider frequency response, notably "triscarboxy-terpyridine Ru-complex" [Ru(2,2',2"-(COOH)3-terpy)(NCS)3], which is efficient right into the low-frequency range of red and IR light. The wide spectral response results in the dye having a deep brown-black color, and is referred to simply as "black dye".[15] The dyes have an excellent chance of converting a photon into an electron, originally around 80% but improving to almost perfect conversion in more recent dyes, the overall efficiency is about 90%, with the "lost" 10% being largely accounted for by the optical losses in top electrode.[7]

A solar cell must be capable of producing electricity for at least twenty years, without a significant decrease in efficiency (lifespan). The "black dye" system was subjected to 50 million cycles, the equivalent of ten years' exposure to the sun in Switzerland. No discernible decrease of the performance was observed. However the dye is subject to breakdown in high-light situations. Over the last decade an extensive research program has been carried out to address these concerns, which were completed in 2007.[7]

The team has also worked on a series of newer dye formulations while the work on the Ru-complex continued. These have included 1-ethyl-3 methylimidazolium tetrocyanoborate [EMIB(CN)4] which is extremely light- and temperature-stable, copper-diselenium [Cu(In,GA)Se2] which offers higher conversion efficiencies, and others with varying special-purpose properties.

DSSc's are still at the start of their development cycle. Efficiency gains are possible and have recently started more widespread study. These include the use of quantum dots for conversion of higher-energy (higher frequency) light into multiple electrons, using solid-state electrolytes for better temperature response, and changing the doping of the TiO2 to better match it with the electrolyte being used.

New developments

2006

The first successful solid-hybrid dye-sensitized solar cells were reported.[14]

To improve electron transport in these solar cells, while maintaining the high surface area needed for dye adsorption, two researchers have designed alternate semiconductor morphologies, such as arrays of nanowires and a combination of nanowires and nanoparticles,to provide a direct path to the electrode via the semiconductor conduction band. Such structures may provide a means to improve the quantum efficiency of DSSCs in the red region of the spectrum, where their performance is currently limited.[16]

On August 2006, to prove the chemical and thermal robustness of the 1-ethyl-3 methylimidazolium tetracyanoborate solar cell, the researchers subjected the devices to heating at 80°C in the dark for 1000 hours, followed by light soaking at 60°C for 1000 hours. After dark heating and light soaking, 90% of the initial photovoltaic efficiency was maintained – the first time such excellent thermal stability has been observed for a liquid electrolyte that exhibits such a high conversion efficiency. Contrary to silicon solar cells, whose performance declines with increasing temperature, the dye-sensitized solar-cell devices were only negligibly influenced when increasing the operating temperature from ambient to 60°C.

April 2007

Wayne Campbell at Massey University, New Zealand, has experimented with a wide variety of organic dyes based on porphyrin.[17] In nature, porphyrin is the basic building block of the hemoproteins, which include chlorophyll in plants and hemoglobin in animals. He reports efficiency on the order of 7.1% using these low-cost dyes.[18]

June 2008

In a joint article published in Nature Materials, Michael Grätzel and colleagues at the Chinese Academy of Sciences demonstrated cell efficiencies of 8.2% using a new solvent-free liquid redox electrolyte consisting of a melt of three salts, as an alternative to using organic solvents as an electrolyte solution. Although the efficiency with this electrolyte is less than the 11% being delivered using the existing iodine-based solutions, the team is confident the efficiency can be improved.[19]

This percentage will no doubt increase in the years ahead and the sight of wind turbines scattered across landscapes will become an increasingly common occurrence. It's all a part of the battle to reduce global warming induced climate change and to reduce our reliance on fossil fuels.

While we're likely most familiar with the huge turbines that crank out electricity for hundreds or thousands of residences, there are now many smaller options available for residential use.

Wind and solar energy connection

It's important to understand that wind is actually a form of solar energy - so by saying that a wind turbine harnesses solar power isn't totally incorrect. Wind is a phenomenon that occurs caused by the uneven heating of the Earth's surface in combination with the spinning of the planet on its axis.

Turbine design

A wind turbine, instead of operating like a fan in your home that uses electricity to create wind, uses wind to create electricity. The blades of the turbine are shaped in such a way that wind causes them to rotate, which spins a low speed shaft with a gear at the end which is connected to another smaller gear on a high speed shaft that runs through a generator housing.

The generator creates electricity using much the same principle as the alternator on your car (depending on the turbine type). A magnetic rotor on the high speed shaft inside the generator housing spins inside loops of copper wire that are wound around an iron core. As the rotor spins around the inside of the core it creates "electromagnetic induction" through the coils that generates an electrical current. That current is then regulated and fed into the grid (or a residential grid connect system) after some modification so that it can be used in our homes or routed into a battery bank for storage. Where a battery bank is used, a regulator prevents overcharging.

The most common wind turbine is the horizontal-axis, which looks somewhat like a traditional windmill, but there are also vertical-axis designs that look similar to an egg-beater or paddle wheel laid on its side.

In the horizontal-axis type, a yaw mechanism in the turbine shaft is utilized to turn the wind turbine rotor into the wind, increasing efficiency. In most cases with wind farm turbines, this is a powered by a small electric motor and computer monitoring.

Turbine size and output

Wind turbines for commercial electricity production usual range from 100 kilowatts to 5 megawatts. At the time of writing, the largest wind turbine in the world had a rotor diameter of 126 m (390 feet) and the potential to generate enough electricity for 5000 households.

A wind turbine for home use has rotors between 8 and 25 feet in diameter and usually has the potential to generate between a few hundred watts and 6 kilowatts of electricity. Some wind turbines can be used in conjunction with a grid connect system.

For every kilowatt hour of electricity produced by wind energy or other green means, approximately 1.5 pounds of carbon is prevented from going into the atmosphere if that electricity had been sourced from coal fired power plants. Carbon dioxide is a major contributor to global warming induced climate change.

Wind speeds needed

A wind turbine usually needs wind speeds of around 10 miles an hour (16kmh) to start generating electricity and optimum wind speed for large turbines is approximately 30 miles per hour ; so they aren't really an option if you're located in an area where winds are usually light and variable, although some models are now being produced that can generate electricity with as little as 5 mile per hour wind speeds - particularly vertical axis models.

Wind speed usually increases with height and where there are no natural or man-made obstructions and this why you'll often see them on hilltops or perhaps in the middle of wheat fields. The wind energy industry has been a boon for many farmers as they can still crop their land with little interference and also generate an income from allowing the turbines on their property. Increasing numbers of wind farms are also being erected offshore.

The blades of a wind turbine rotate at a rate of between 10 to 50 revolutions per minute. In a situation where wind speeds are excessive, for example if there's a gale, the turbine automatically shuts down to prevent damage.

Turbine lifespan

The lifespan of a modern turbine is pegged at around 120 000 hours or 20-25 years, but they aren't totally maintenance free. As they contain moving components, some parts will need to be replaced during their working life. From what I've researched, the cost of maintenance and parts replacement is around the 1 cent USD/ AU per kWh or 1.5 to 2 per cent annually of the original turbine cost.

Environmental impact

Wind turbines aren't overly noisy - mechanical noise is minimum these days and you'll mostly hear the swoosh of the blades passing the tower. Of course, if you're living close to a large wind farm, it could present some noise issues; but most countries have regulations regarding the placement of wind farms in relation to residential areas.

Wind turbines are created from fiberglass, plastics, aluminium, copper, steel and various other metals, so they do have an impact on the environment in that respect and there's also the energy used to to manufacture the turbine. Many turbine parts are recyclable and it's my understanding the amount of energy used in manufacture is balanced out within six to eight months after being commissioned.

Wind farms do have an impact on birds - there have been recorded cases of birds being killed by rotor blades when they fly into them; but there's a great deal of research being carried out to try and minimize the problem. It's also an issue taken into consideration in most countries when choosing a location for a wind farm in relation to bird migratory patterns.

Costs and regulation for residential turbines

Turbines used in residential situations are much quieter than their wind farm counterparts, but you'll need to check with your local authorities as they are still not permitted in some areas - this being the case, your best options for renewable energy is solar power. If you do meet resistance with your local council, talk to them about vertical turbine options as these emit lower noise, have a lower profile and are considered to be generally more aesthetically pleasing than their horizontal axis counterparts. As local government tends to be behind the times with technological developments in renewable energy, it doesn't hurt to raise the possibility of that alternative.

Wind turbines for home use vary in price and greatly depend on your electricity needs vs. wind availability, but you can expect to pay around $12,000 to cater for the average home. However, bear in mind that cost can be greatly offset by renewable energy rebates offered by many governments.

Many people think that wind turbines are ugly, and I tend to agree; but I feel that way about most things man made that are added to a natural landscape. Aesthetics aside, the other point that people should bear in mind that if we want to maintain the level of comfort we've grown accustomed to in our modern lives, there will always be some sort of price to pay beyond dollars and cents.

If I had to choose between living close by to a wind farm or a coal fired electricity generation plant, I'd certainly opt for the wind farm and I'd definitely consider a residential model turbine if wind was a reliable factor in my area - there's nothing quite like the feeling of gaining independence through your own electricity generation :).